System Identification Theory Approach to Cohesive Sediment Transport Modelling

Two aspects of the modelling sediment transport are investigated. One is the univariate time series modelling the current velocity dynamics. The other is the multivariate time series modelling the suspended sediment concentration dynamics. Cohesive sediment dynamics and numerical sediment transport model are reviewed and investigated. The system identification theory and time series analysis method are developed and applied to set up the time series model for current velocity and suspended sediment dynamics. In this thesis, the cohesive sediment dynamics is considered as an unknown stochastic system to be identified. The study includes the model structure determination, system order estimation and parameter identification based on the real data collected from relevant estuaries and coastal areas. The strong consistency and convergence rate of recursive least squares parameter identification method for a class of time series model are given and the simulation results show that the time series modelling of sediment dynamics is accurate both in data fitting and prediction in different estuarine and coastal areas. It is well known that cohesive sediment dynamics is a very complicated process and it contains a lot of physical, chemical, biological and ocean geographical factors which are still not very well understood. The numerical modelling techniques at present are still not good enough for quantitative analysis. The time series modelling is first introduced in this thesis to set up cohesive sediment transport model and the quantitative description and analysis of current velocity and suspended sediment concentration dynamics, which provides a novel tool to investigate cohesive sediment dynamics and to achieve a better understanding of its underlying character

Rosiglitazone Suppresses the Growth and Invasiveness of SGC-7901 Gastric Cancer Cells and Angiogenesis In Vitro via PPARγ Dependent and Independent Mechanisms

Although thiazolidinediones (TZDs) were found to be ligands for peroxisome proliferators-activated receptorγ (PPARγ), the mechanism by which TZDs exert their anticancer effect remains unclear. Furthermore, the effect of TZDs on metastatic and angiogenesis potential of cancer cells is unknown. Our results in this paper show that rosiglitazone inhibited SGC-7901 gastric cancer cells growth, caused G1 cell cycle arrest and induced apoptosis in a dose-dependent manner. The effects of rosiglitazone on SGC-7901 cancer cells were completely reversed by treatment with PPARγ antagonist GW9662. Rosiglitazone inhibited SGC-7901 cell migration, invasiveness, and the expression of MMP-2 in dose-dependent manner via PPARγ-independent manner. Rosiglitazone reduced the VEGF induced angiogenesis of HUVEC in dose-dependent manner through PPARγ-dependent pathway. Moreover, rosiglitazone did not affect the expression of VEGF by SGC-7901 cells. Our results demonstrated that by PPARγ ligand, rosiglitazone inhibited growth and invasiveness of SGC-7901 gastric cancer cells and angiogenesis in vitro via PPARγ-dependent or -independent pathway

Draft genome sequence of Acidithiobacillus ferrooxidans YQH-1

AbstractAcidithiobacillus ferrooxidans YQH-1 is a moderate acidophilic bacterium isolated from a river in a volcano of Northeast China. Here, we describe the draft genome of strain YQH-1, which was assembled into 123 contigs containing 3,111,222bp with a G+C content of 58.63%. A large number of genes related to carbon dioxide fixation, dinitrogen fixation, pH tolerance, heavy metal detoxification, and oxidative stress defense were detected. The genome sequence can be accessed at DDBJ/EMBL/GenBank under the accession no. LJBT00000000

Arsenic tolerance and bioleaching fromrealgar based on response surface methodology by Acidithiobacillus ferrooxidans isolated from Wudalianchi volcanic lake, northeast China

Background: Traditional methods of obtaining arsenic have disadvantages such as high cost and high energy consumption. Realgar is one of the most abundant arsenic sulphide minerals and usually treated as waste in industry. The aim of the present study was to screen an arsenic tolerant bacterium used for bioleaching arsenic from realgar. Results: An acidophilic iron-oxidizing bacterium BYQ-12 was isolated from Wudalianchi volcanic lake in northeast China. BYQ-12 was a motile, rod-shaped gram-negative bacterium with an optimum growth at 30\ub0C and pH 2.5. 16S rDNA phylogeny showed that BYQ-12 was a new strain of Acidithiobacillus ferrooxidans . The inhibitory concentrations (ICs) of arsenite and arsenate were 32 and 64 mM, respectively. A significant second-order model was established using a Box\u2013Behnken design of response surface methodology (BBD-RSM) and it estimated that a maximum arsenic bioleaching rate (73.97%) could be obtained when the pulp concentration, pH and initial ferrous ion concentration were set at optimized values of 0.95% w/v, 1.74 and 3.68 g/L, respectively. SEM, EDS and XRD analyses also revealed that there was direct bioleaching besides indirect electrochemical leaching in the arsenic bioleaching system. Conclusion: Fromthis workwe were successful in isolating an acidophilic, arsenic tolerant ferrous iron-oxidizing bacterium. The BBD-RSM analysis showed that maximum arsenic bioleaching rate obtained under optimum conditions, and the most effective factor for arsenic leaching was initial ferrous ion concentration. These revealed that BYQ-12 could be used for bioleaching of arsenic from arsenical minerals

Odor, Not Performance, Dictates \u3cem\u3eBemisia tabaci\u3c/em\u3e\u27s Selection Between Healthy and Virus Infected Plants

Although, insect herbivores are generally thought to select hosts that favor the fitness of their progeny, this “mother-knows-best” hypothesis may be challenged by the presence of a plant virus. Our previous study showed that the whitefly, Bemisia tabaci, the obligate vector for transmitting Tomato yellow leaf curl virus (TYLCV), preferred to settle and oviposit on TYLCV-infected rather than healthy host plant, Datura stramonium. The performances of B. tabaci larvae and adults were indeed improved on virus-infected D. stramonium, which is consistent with “mother-knows-best” hypothesis. In this study, B. tabaci Q displayed the same preference to settle and oviposit on Tomato spotted wilt virus (TSWV)-infected host plants, D. stramonium and Capsicum annuum, respectively. As a non-vector of TSWV, however, insect performance was impaired since adult body size, longevity, survival, and fecundity were reduced in TSWV infected D. stramonium. This appears to be an odor-mediated behavior, as plant volatile profiles are modified by viral infection. Infected plants have reduced quantities of o-xylene and α-pinene, and increased levels of phenol and 2-ethyl-1-hexanol in their headspace. Subsequent behavior experiments showed that o-xylene and α-pinene are repellant, while phenol and 2-ethyl-1-hexanol are attractive. This indicates that the preference of B. tabaci for virus-infected plants is modulated by the dynamic changes in the volatile profiles rather than the subsequent performances on virus-infected plants